Michelle Amanada Jackson

A study of cardiovascular function under controlled and spontaneous ventilation in isoflurane-medetomidine anaesthetized horses

OBJECTIVE To determine, in mildly hypercapnic horses under isoflurane-medetomidine balanced anaesthesia, whether there is a difference in cardiovascular function between spontaneous ventilation (SV) and intermittent positive pressure ventilation (IPPV). STUDY DESIGN Prospective randomized clinical study. ANIMALS Sixty horses, undergoing elective surgical procedures under general anaesthesia: ASA classification I or II. METHODS Horses were sedated with medetomidine and anaesthesia was induced with ketamine and diazepam. Anaesthesia was maintained with isoflurane and a constant rate infusion of medetomidine. Horses were assigned to either SV or IPPV for the duration of anaesthesia. Horses in group IPPV were maintained mildly hypercapnic (arterial partial pressure of carbon dioxide (PaCO(2)) 50-60 mmHg, 6.7-8 kPa). Mean arterial blood pressure (MAP) was maintained above 70 mmHg by an infusion of dobutamine administered to effect. Heart rate (HR), respiratory rate (f(R)), arterial blood pressure and inspiratory and expiratory gases were monitored continuously. A bolus of ketamine was administered when horses showed nystagmus. Cardiac output was measured using lithium dilution. Arterial blood-gas analysis was performed regularly. Recovery time was noted and recovery quality scored. RESULTS There were no differences between groups concerning age, weight, body position during anaesthesia and anaesthetic duration. Respiratory rate was significantly higher in group IPPV. Significantly more horses in group IPPV received supplemental ketamine. There were no other significant differences between groups. All horses recovered from anaesthesia without complications. CONCLUSIONS There was no difference in cardiovascular function in horses undergoing elective surgery during isoflurane-medetomidine anaesthesia with SV in comparison with IPPV, provided the horses are maintained slightly hypercapnic. CLINICAL RELEVANCE In horses with health status ASA I and II, cardiovascular function under general anaesthesia is equal with or without IPPV if the PaCO(2) is maintained at 50-60 mmHg.

Evaluation of a Motorized Morcellator for Laparoscopic Removal of Granulosa‐Theca Cell Tumors in Standing Mares

OBJECTIVE To describe a motorized morcellator technique for laparoscopic removal of granulosa-theca cell tumors (GCT) in standing mares and to evaluate long-term outcome. STUDY DESIGN Case series. ANIMALS Mares (n=7) aged 4-15 years, with unilateral GCT. METHODS Tumor size was determined by transrectal palpation and ultrasonography. Standing sedated mares had 3 laparoscopic portal sites in the paralumbar fossa. After laparoscopic observation of the GCT, the mesovarium was desensitized, the ovarian pedicle transected with a LigaSure device, and the ovary grasped with forceps and cut in cylindrical tissue blocks using a motorized morcellator. Tissue blocks were removed through the laparoscopic sleeve. Outcome was determined by telephone interview of owners 6-40 months after surgery. RESULTS Estimated ultrasonographic median GCT diameter was 17 cm (range, 10-22 cm). Surgical time was 2-4.5 hours. There were no surgical complications. Two mares had mild subcutaneous emphysema at the portals after surgery. Convalescence was short, owners were satisfied with cosmetic outcome, and clinical signs associated with GCT did not recur. CONCLUSION The motorized morcellator allows piecemeal removal of large GCT through a relatively small laparoscopic portal. Surgical complications were rare and the cosmetic outcome is favorable. CLINICAL RELEVANCE A motorized morcellator is a safe and minimally invasive technique for laparoscopic removal of GCT in mares.

Results and complications of a novel technique for primary castration with an inguinal approach in horses

REASONS FOR PERFORMING STUDY Complications associated with equine castration can have medical and financial consequences. This retrospective study investigated a novel method of castration via an inguinal approach in mature stallions and compared the incidence of complications with other methods. HYPOTHESIS Castration via an inguinal approach has a low complication rate at the site of surgery compared with other castration techniques. METHODS Mature stallions (n = 238) were castrated under general anaesthesia in dorsal recumbency using an inguinal approach. The vaginal process was incised, the spermatic cord ligated twice and the testis removed. After suturing, the vaginal process and one or 2 layers of fascia, the subcutis and cutis were closed in a simple continuous pattern. RESULTS Five of 238 (2.1%) horses had post operative haemorrhage and a haematoma in the scrotal region, which required additional treatment. All horses made a full recovery. Five of 238 (2.1%) of the horses had a post operative respiratory infection, which resolved with antibiotic therapy. Sixteen of 238 (8.8%) had transient signs of colic shortly after surgery. CONCLUSION This technique of castration with an inguinal approach had a low incidence of complications at the site of surgery compared with other methods. An inguinal approach and leaving the vaginal tunic in situ may cause less soft tissue trauma than a scrotal approach.

Treatment of type 2 and 4 olecranon fractures with locking compression plate osteosynthesis in horses: A prospective study (2002–2008)

This prospective study describes a series of 18 olecranon fractures in 16 horses that were treated with locking compression plates (LCP). Twelve of the 18 fractures were simple (type 2), whereas six were comminuted (type 4). Six fractures were open and 12 were closed. Each horse underwent LCP osteosynthesis consisting of open reduction and application of one or two LCP. Complete fracture healing was achieved in 13 horses. Three horses had to be euthanatized: two because of severe infection and one because of a comminuted radial fracture 11 days after fixation of the olecranon fracture. Complications encountered after discharge of the horses from the Equine Hospital at the Vetsuisse Faculty (University of Zurich) included implant infection (n=2) and lameness (n=3), which were successfully treated with implant removal. Despite being easier to use, LCP osteosynthesis resulted in a clinical outcome similar to DCP osteosynthesis.

Skin malformations in a neonatal foal tested homozygous positive for Warmblood Fragile Foal Syndrome

BackgroundSkin malformations that resembled manifestations of Ehlers-Danlos-Syndrome were described in a variety of domestic animals during the last century as cutis hyperelastica, hyperelastosis cutis, dermatosparaxis, dermal/collagen dysplasia, dermal/cutaneous asthenia or Ehlers-Danlos-like syndrome/s. In 2007, the mutation responsible for Hereditary Equine Regional Dermal Asthenia (HERDA) in Quarter Horses was discovered. Several case reports are available for similar malformations in other breeds than Quarter Horses (Draught Horses, Arabians, and Thoroughbreds) including four case reports for Warmblood horses. Since 2013, a genetic test for the Warmblood Fragile Foal Syndrome Type 1 (WFFS), interrogating the causative point mutation in the equine procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1 (PLOD1, or lysyl hydroxylase 1) gene, has become available. Only limited data are available on the occurrence rate and clinical characteristics of this newly detected genetic disease in horses. In humans mutations in this gene are associated with Ehlers-Danlos Syndrome Type VI (kyphoscoliotic form).Case presentationThis is the first report describing the clinical and histopathological findings in a foal confirmed to be homozygous positive for WFFS. The Warmblood filly was born with very thin, friable skin, skin lesions on the legs and the head, and an open abdomen. These abnormalities required euthanasia just after delivery. Histologic examination revealed abnormally thin dermis, markedly reduced amounts of dermal collagen bundles, with loosely orientation and abnormally large spaces between deep dermal fibers.ConclusionWFFS is a novel genetic disease in horses and should be considered in cases of abortion, stillbirth, skin lesions and malformations of the skin in neonatal foals. Genetic testing of suspicious cases will contribute to evaluate the frequency of occurrence of clinical WFFS cases and its relevance for the horse population.

Anatomie der Griffelbeine und ihrer Umgebung unter besonderer Berücksichtigung der Faszien

Diese Arbeit untersucht die Ossa metacarpalia/Ossa metatarsalia II und IV beim Pferd und im Besonderen die Weichteilgewebe um die Griffelbeine. Dabei wurden die Fascia metacarpi palmaris/Fascia metatarsi plantaris, die Ligamenta metacarpea/metatarsea interossea und die Faserbundel, welche distal vom Griffelbeinknopfchen entspringen, anatomisch genau beschrieben. Die Gliedmassen von 5 geschlachteten oder euthanasierten Pferden wurden gesammelt und sowohl makroskopisch als auch mikroskopisch untersucht. Die Fascia metacarpi palmaris/Fascia metatarsi plantaris stellte sich als eine sehr stabile Struktur dar, welche die Griffelbeine fest mit der Umgebung verbindet. Die Ligamenta metacarpea/metatarsea interossea, welche die Verbindung zwischen Griffelbeinen und Rohrbein darstellen, zeigen erhebliche Unterschiede von Pferd zu Pferd. Makroskopische Untersuchungen des Weichteilgewebes distal an den Griffelbeinen zeigt eine Bandstruktur, die am Griffelbeinknopfchen entspringt und in dorso-distaler Richtung verlauft.

Epidemiology of fractures: The role of kick injuries in equine fractures

BACKGROUND Fractures occur commonly in equids and often are associated with complications and a poor outcome. There are no reports on the epidemiology of fractures in a heterogeneous equine population. OBJECTIVES To study the epidemiology of fractures in a heterogeneous equine population, focusing on differences between fractures resulting from a kick and fractures, resulting from other causes and investigating predictors for recovery. STUDY DESIGN Retrospective case series. METHODS Data of all equids presented to the Equine Department, Vetsuisse Faculty, University of Zurich between 1990 and 2014 and diagnosed with a fracture were reviewed and those with a known cause were included in this study. Mann-Whitney and chi-squared tests were used to compare recovery rates of fractures resulting from a kick and fractures resulting from other causes, and a logistic regression was carried out for multivariate analysis of the most important factors affecting recovery. RESULTS Here, 1144 cases fulfilled the inclusion criteria. Of all fractures (with a known cause), 43.6% were the result of a kick from another equid. Kicks often produced open fractures (44.7%) that involved bones of the limbs (85.6%). Overall recovery was 70.1%. Logistic regression showed that high-grade lameness accompanying the fracture and severe comminution negatively affected recovery. MAIN LIMITATIONS The equids in this study were drawn from a referred population, which likely precluded the inclusion of both minor fractures and catastrophic fractures that necessitated immediate euthanasia. Moreover, many cases were excluded because the cause of the fracture could not be determined from the patient record. CONCLUSIONS Kicks are the most common cause of fractures in a heterogeneous equine population and measures to reduce the incidence of kicks are necessary in group-housing systems.

Direct approach to the nasal cavity through a bone flap for the treatment of a large nasal cyst

A 21-year-old Warmblood mare was referred to the Equine Department, Vetsuisse Faculty, University of Zurich, because of recurrent unilateral nasal discharge 3 months after partial removal of a large cyst from the left maxillary and frontal sinuses. Endoscopic, radiographic and computed tomographic examinations showed that the remnant of the cyst, which originally had extended from the left maxillary and frontal sinuses into the left nasal cavity, had expanded and was obliterating the left middle nasal meatus. A direct surgical approach to the cyst through the left nasal and maxillary bones rostral to the facial crest was chosen, which allowed evaluation and removal of the entire cyst. Endoscopic examination 3 days post operatively showed no remnants of the cyst, and the mare was discharged in good health. Re-examination one year later showed no recurrence of the cyst.